Evolang 2010
Abstract: Production of /a i u/ from feeding
PRODUCTION OF THE VOWELS /a i u/ BASED ON AN ARTICULATORY MODEL OF FEEDING ANTOINE SERRURIER AND ANNA BARNEY Institute of Sound and Vibration Research University of Southampton, UK
1. Introduction Both ontogenetically and phylogenetically feeding tasks precede speaking tasks, two of the major functions of the human vocal tract (VT). Researchers have therefore suggested that speech cyclicity, in particular tongue movements, derives from feeding cyclicity (MacNeilage, 1998; Hiiemae and Palmer 2003). Our study explores this hypothesis using articulatory modelling to determine if the tongue movements in speech are a subset of those in feeding. In a previous study (Serrurier et al., 2008) we used ElectroMagnetic Articulography, however this is an invasive technique that further gives no VT boundaries. To overcome these limitations we here use Digital VideoFluoroscopy (DVF). We wish to explore if we can extract from the raw data and from an articulatory model based on the data, articulations which are geometrically and acoustically close to the quantal vowels /a i u/. Their typical F1-F2 values and their typical geometric shape constitute respectively our acoustic and articulatory targets. 2. Method and results Two swallows of pourable custard were recorded with DVF on a single female subject. Each image was manually segmented to extract the tongue contour. Following Serrurier et al. (2008), a mid-sagittal articulatory model of the tongue was built. Three tongue articulations optimally approaching our two targets simultaneously were extracted from the raw data and also reconstructed from the model. The articulatory model has the advantage over the raw data of encompassing all task-derivable articulations theoretically producible by the tongue. The six articulations were placed in a fixed, midsagittal VT outline; the area functions in 3D were derived; the planar acoustic wave propagation was
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Evolang 2010
Abstract: Production of /a i u/ from feeding
simulated and F1-F2 (see Figure 1) values were extracted. For the articulations extracted from the data, none of the F1-F2 points are inside the target ellipses; those computed from the model fall on the border or just inside. 0
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Figure 1. Position in the F1-F2 plane of the six articulations extracted in the study (data = dashed line; model = solid line). The ellipses for the vowels are adapted from Peterson and Barney (1952).
3. Conclusion The recorded feeding movements allow articulation of tongue shapes close to typical midsagittal patterns found for /a i u/ with predicted F1-F2 just touching the corresponding ellipses. It seems thus just reasonable to claim that speech movements are a subset of feeding movements based on this data set. This study complements our previous study with a new recording technique and further subject and supports its general conclusion, that speech movements could have evolved from feeding movements, with the caveat that we have neglected any control considerations. A similar approach using ape data had been considered but could not been carried out due to the lack of data. Acknowledgements The authors wish to acknowledge the help of A. Matos, R. Santos, Dr M. Collins and Dr P. Badin. This work is part of the HandtoMouth project (EC NEST initiative).
References Hiiemae, K. M. & Palmer, J. B. (2003). Tongue Movements in feeding and speech. Crit. Rev. Oral Biol. M., 14(6), 413-429. MacNeilage, P. F. (1998). The frame/content theory of evolution of speech production. Behav. Brain Sci., 21, 499-546. Peterson, G. E. & Barney, H. L. (1952). Control methods used in a study of the vowels. J. Acoust. Soc. Am., 24, 175-184. Serrurier, A., Barney, A., Badin, P., Boë, L.-J. & Savariaux, C. (2008). Comparative articulatory modelling of the tongue in speech and feeding. Proc. 8th ISSP, 325-328.
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